Apparatus for the reduction of pressure from mixtures of liquids with gases



fsepf. 3o, 1941. F-KQEHLER HAL 2,257,173

APPARATUS FOR THE REDUCTION OF PRESSURE FROM MIXTURES OF LIQUIDS WITH GASES Filed July 8, 41938 3 Sheets-Sheet l Sept. 30, 1941. F. KOEHLER :TAL 2,257,173

APPARATUS FOR THE REDUCTION 0F PRESSURE FROM MIXTURES 0F LIQUIDS WITH GASES Filed July 8, 1938, 3 She'ets-Sheet 2 Sept. 30, 1941. F, KOEHLER ETAL 2,257,173 ARPARATUS FOR THE REDUCTION oF PRESSURE FROM MIxTUREs oF LIQUIDS WITH GASES Filed July 8, 1958 3 Sheets-Sheet 3 n *l mimi" I Patented Sept. 30, 1941.

APPARATUS Foa THE aEnUcTIoN oF Passsuns FaoM MixTUnEs or LiQUms wrm GASES Franz Koehler and Max Josenhans, Leuna, Germany, assignors to Standard Catalytic Colnpany, a corporation of-Delaware Application July 8, 1938, Serial No. 218,244 .t

In Germany July Z9, 1937 1o claims. (ci. 1er- 111) The present invention relates to improvements in an apparatus for the reduction of pressure from mixtures of liquids with gases.

When liquids under high pressure, in particular those which contain in dispersion more or less solid constituents, are to be reduced from pressure through valves or throttle members, the

operation not only results in considerable loss of energy but also causes a greatV wear of the said members and moreover the properties of the product are impaired by the eddies thus formed so that diilicultes may be encountered in the further working up of the same.

In order to make use of the energy set free during the reduction of the pressure on such .liquids it has already been proposed to use piston pressure-reduction machines having one or more high pressure cylinders in which the energy of the product reduced from pressure is conveyed by pistons to other products, especially, liquid products, which are to be brought to a high pressure. The said troubles readily arise in such machines, however, because in these machines the reduction of pressure takes place in the outlet valve and in part also in the inlet valve.

The said difliculties are avoided for the greater part by carrying out the reduction of pressure ofhighly compressed liquids in cylinder spaces of power machines in which the energy of the inilowing substances is utilized by plungers by way of crank drive and ywheel, whereby only a part of the substance reduced from pressure is ejected with the aid of the plunger while the remainder is recompressed to approximately the initial pressure of the product before a further part of the same is let in to the cylinder of th'e pressure-reduction machine.

This method of pressure-reduction has, however, proved unsuitable for reducing the pressure onvliquids containing gases, especially when the gas content of the said liquids uctuates strongly. Because of the nature of their driving ably aggravates operation. By remaining in the expansion stroke in the case of under-pressure there is the danger of sucking in air and forming explosive mixtures in the case of reducing the pressure on mixtures containing hydrocarbons Y or hydrogen.

Pressure-reduction apparatus which are coupled with crank drive and flywheel, however, also are attended inoperation by great danger because in the case of stoppages in the valves,

- conduits or the like, which may readily occur especially when reducing the pressure on pasty liquids, high excess pressures may be produced .by the ilywheel action and these may destroy the machines and conduits.

It has also been proposed for the reduction `of pressure on liquids, which may contain solids, to employ piston pressure reduction machines containing several high pressure cylinders in which by means of a piston movable in the pressure reduction cylinder chamber the energy of the products to be reduced in pressure is transferred. to a liquid in another cylinder chamber. It has been proposed in this operation to employ two auxiliary liquids one being under high pressure and the other under low pressure. In these known machines working with auxiliary liquids the main aim is to avoid, in cases when the positively controlled inlet and outlet valves stick, that both of said valves are simultaneously open which would lead to aviolent breaking through of liquid with consequent damage to the apparatus. These machines are intended to operate in such a manner that a higher pressure set up on a portion of the product reduced in pressure remaining in the cylinder by recompression thereof after the mechanism these machines cannot be so conf structed that the degree of pressure reduction either remain arrestedin the compression stroke shortly before the final position of the plunger or, in the case of under-pressure, in the ex- -fpansion stroke. yZln both cases, the machine must always be started again and this considerejection stroke positively opens the inlet valve and prevents the outlet valve from opening.

In the operation and construction of these machines the insight was lacking that during the admittance of material to be reduced in pressure into the pressure reduction cylinder a violent rush into the pressure reduction cylinder of the material causing both anA undesirable change of its quality and also erosion more particularly in the inlet valve, must be avoided.

We have now found that all drawbacks of the known apparatus can .be avoided by using for the reductionof pressure from mixtures of liquids with gases and, if desired, solid substances which are under ,high pressure an apparatus which vcomprises a cylinder having a iloating member therein, means for forcing said floating member toward one end of the cylinder, means for conducting the working iluid into the cylinder with` exerted by the rst named means, this force being slightly less than that of the working uid acting on the @floating member, means for cutting off the supply of said working fluid, means for reducing the force applied to` the floating member by said rst named means while conlining the working fluid within the cylinder thereby reducing vthe pressure on said conned working fluid, and means for expelling said working uid at the reduced pressure.

By using this apparatus the reduction. of pressure-is carried out by bringing the mixture to be reduced from pressure (initial product) without substantial loss in pressure into the cylinder'of ,a pressure reduction machine against a piston pressure produced by a high pressure auxiliary liquid, which pressure is substantially the same or only slightly lower than the pressure to be reduced, untilthe cylinder has been Vfilled to a predetermined degree, stopping the supply of initial product, reducing the piston pressure by changing over toa low pressure "auxiliary liquid whereby the piston continues to move until the desired'degree of pressure reduction on -the initial product is attained, reversing the direction of movement of the piston and ejecting the material reduced in pressure from the cylinder by the pressure of the 'low pressure auxiliary liquid untilonly so much material remains in Athe cylinder to form a brake uid, closing the outlet valve, changing over to be high pressure auxiliary liquid thereby bringing the brake fluid to approximately the pressure of the initial product and repeating the cycle of operations.

-The brake uid has approximately the same pressure as that of the initial product when the latter can be admitted into the pressure reduction chamber without a violent rush of material occurring. The pressures of the two fluids should be as nearly as possible the same. The diierence in pressure lshould preferably be lessthan atmospheres and not exceed I30 atmospheres.

By the recompression of the brake uid to approximately the same pressure as that of the initial product the otherwise unavoidable erosion of the inlet valve and impairing of the properties l of the product are avoided.

'Ihe said two auxiliary liquids are usually the i same, although where convenient they may also be different. t

Invthe known pressure reduction machines operating with auxiliary liquid the opening and closing of the inlet and outlet valves was only made possible when a. control device mechani-` cally actuated by the movements of the pistonV and provided with a high pressure liquid, allows of the opening or closing of the said valves. Obviously such a machine in which the opening and closing of the inlet and outlet valves is dependenton the positions of the piston, cannot automatically adjust itself to fluctuating contents of gases in the liquids such as always occurin au` tomatically high pressure reactions. In these machines the insight was lacking that the machine must automatically adjust itself to the continuously changing gas contentof the material to be reduced in pressure. y

In order to adjust the operation of the machine in accordance with .the present invention p to the fluctuating gas content of the initial product to be reduced in` pressure, itis necessary to make the' control of the inlet and outlet Avalves tween the surfaceof the hydraulically controlled valves and by the internalA pressure -in the pressure release machine in co-operation with check valves. c

How the invention may be carried out in practice will bel further describedfwith lreference to the accompanying drawings whichshow examples of apparatus in accordance with this invention but the invention is notv restricted to the particular examples shown.

Figure l is a diagrammaticview of a pressure f reduction cylinder. A

Figure 2 is a diagrammatic view of la ow control system for the cylinder. i y

Figures 3, 4, 5, and -showthe cylinder and flow control system under different Aoperating conditions.

On one side of the Y an inlet valve A and an outlet"v valve 13l rfor the product to be reduced from lpressure. Theother side of` the cylinder acts as a'pump. -The valves D and F are normal check'valves in the circuits of which the valves C and E'are interposedas controlled valves. The diameter'of-the piston rod is so dimensioned thatthe surface' of the piston diminished by the :cross-sectionv of the piston rod brings an auxiliary l"liquid introduced' above the same through thevalves C and D to a pressure about 10 per cent higher than theoriginal pressure of the initial product' acting on the other side of the piston. It is very desirable that the high pressure auxiliary` liquidf should lhave al higher pressure than that of the material to be reduced in pressure because thereby a good lubrication of piston kKfis attained. of particularimportance in the pressure reductio'nof liquidscontaining solid material in suspension since the higher -pressure of the auxiliary liquid prevents solid matter from pressing itself in bechamber and the piston wall.' cordance with'the present invention -is preferably upright. is particul.f irlyA desirable in pressure reduction of liquids containing solids of higher specic gravity than .that of the liquid since then the bulk of the solids sinks to the bottom of the cylinder and does not disturb the,

movement of the piston... Furthermore inl an is present to act as thebrake uid. i

Through the valveV C,v which is constructedv as,

a controllable check valve, and the checl; valve D there ow's intothe cylinder aliquid under low:

pressure which forces thel piston downwardsZ with opened outlet valve B (see Figure 6). Shortly before the n'al position of the piston, the outlet.

valve B is closed. The controllable check valve E is then opened, with the result that from the conduit connected thereto a liquid under a pres-v sure about 10 per cent higher than that o'n the product to be reduced vfrom pressure flows into` the cylinder, and the said liquid produces a'liigh counter-pressure on the pump -side (see Figure 3). There is no diiiiculty in constructing the cylinderttom and the piston so that even in'the case' pressures prevailing cylinderr there situated The pressure reduction cylinder in acoi products containing large amounts of gas there remains in the cylinder a residue of liquid mixture after each ejection of the pressure-reduced product and after closure of the outlet valve B which serves as a brake liquid for braking the piston and for rapidly obtainingthe necessary counter-pressure between piston and inlet valve. If it is desired to eliminate the liquid product completely after each stroke and to employ gas as the brake fluid, this may be attained simply by appropriate construction of the piston; cylinder bottom and the arrangement of the outlet valve. In this case also, by the positive and correctly4 timed closure of the outlet valve B which depends on the position of the piston, the gas remaining beneath the piston is compressed by the high counter-pressure of the liquid above they piston to approximately the pressure of the pressure-reduction product before the inlet valve A. The inlet valve Ais then/opened, the initial product thus being slulced into the cylinder without fall in pressure (see Figure 4). T he piston is then moved upwards, whereby the liquid situated on the pump side of the piston is moved through the check valves E and F into the high pressure liquidI conduit O. When the cylinder has been iilled to a predetermined extent, lthe piston rod actuates a usual control in known manner. The inlet valve A is ilrst closed, whereupon the check valves F and E close and the controllable check valve C is opened, whereupon the initial product is reduced to the lower pressure of the low-pressure liquid in ther conduit n, while moving the piston upwards again (see Figure 5). Only a'fter attainng this low pressure, which by making the length of the cylinder sufiiciently great is always the same even with initial products having varying lgas content, is the outlet valve B opened and the product, which is now reduced in pressure, ejected from the cylinder by the liquid ilowing in underlow pressure through the valves C and D (see Figure 6).

The manner in which the said positive movement is obtained is illustrated in the control diagram in Figure 2. 0

By the movement of the piston there is effected in known manner the movement of the piston rod of an auxiliary controlling slide S by which a driving agent, which may be taken from the liquid moved through the machine at high pressure, is controlled. The auxiliary controlling slide has five attachments. The pressure liquid enters the slide through the@y pipe a and passes, according to the position'o the piston inthe slide, through g ori fromv the slide into the pressure distributing pipes to the cylinders of the hydraulically controlled valves, in, order to flow back after having been reduced from pressureA through the two pipes g or i into the slide and to flow away through the pipe f. In the position shown the pressure liquid enters the pipe y from lthe left-hand section of the cylinder of slide l S and returns after reduction from pressure from the controlling cylinders of the valves through the pipe i to the right-hand section of the said cylinder of the controlling slide which it leaves through the pipe The connecting pipes between the auxiliary controlling slide S and the cylinders of the controlling pistons b,

c, d and e are g and i. Of the groups of pipes g and i there are four branches g1, g2, ga and g4 and t1, i2, i3 and i4 which lead to the controlling cylinders of the hydraulically actuated valves. In the pipes g2. ya and i2, i3 there are situated,

-the controlling slide S through D1 directly behind branched or from a or i, the throttle valves D1, D2, Da and D4 with which the speed of the controlling liquid and consequently the movement of the valves is regulated.. In the pipes y1 and i1 tion, the check valves close, so that for the controlling liquid flowing back from the controlling cylinders of the valves there is 4only open the way through the throttle valves to the controlling slide.

, In the pipe is, between the outlet from the controlling cylinder d of the valve C and D1, there. is arranged a stop valve V1 in the form of an overflow valve. On the stem of this valve there is a piston the diameter of which is greater than that of the valve cone. The space in the cylinder which communicates with that face of the piston upon which pressure acts to close the valve is iny connection with the part of the pipe 'in between D2 andthe outlet from the controlling cylinder b of the valve A. In shunt connection with the stop valveVi there is situated in the pipe ia the check valve Rs, which prevents the direct flow of the controlling liquid from the controlling cylinder d of the valve C through D1, but allows. the ow of the pressure liquid from to `d. A second stop valve V2 is situated in the partof the pipe in between D2 and ther outlet of the controlling cylinder c of the outlet valve B. The space in the cylinder which communicates with that face of the piston of 'V2 upon which pressure acts to close the valve Ais in connection with the pump chamber of the pressure-reduction cylinder Z1 through line l.

In the pipe ya, -between D4 and the outlet of the controlling cylinder e of the valve E, there is situated a stop valve Vs of which'the space in the cylinder which communicates with that face of thev piston upon-which pressure acts to close the valve is connected with the part of the pipe g2 coming from the outlet of the controlling cylinder c. In shunt with the stop valve V3 there is situated in the pipe gs a check valve Rey which prevents the direct flow of the controlling .cylintween V4 and the outlet of the controlling cylinder b,; a stop valve Vs. This stop valve is in the form of a spring-loaded valve which is always held closed by the spring. A smaller piston of this valve is connected by the pipe l with the pump chamber of the .pressure-reduction cylinder Z and only press s up the stop valve V5 at a certain internal pre ure of the pump chamber -l of the c'ylinder Z. '-If the auxiliary controlling slide S be brought irito the position shown in Figure 2, the pressure liquid flowing through quand g can firstly enter the points where theyv are.

' Sis reversed in known 'in through a and i can trolling cylinder c.

` escapes through the thro through the auxiliary on the valve spindle sid through the check valve R1 into the controlling cylinder b on the side which communicates with that phase of the piston upon which pressure acts'to close thevalve operated thereby, secondly through the checl-x` valve R3 into the controlling cylinder c on the side of the valve spindle and thirdly into the controlling cylinder d. The liquid situated on the valve spindle side of thecontrolling cylinder b canyescapethrough the throttle valve D2, through i2 and through the auxiliary controlling slide S to f. The dam pressure formed during the piston movement of the controlling piston before Dz is conveyed through a pipe tov the piston of the stop valve v1 and holds this at mst closed untii the stroke of the piston in the controlling cylinder b is ended and the dam pressure in front -of D2 has fallen. Only thereafter can thepiston .of the controlling cylinder d be set in action bythe pressure liquid owing through g4. 'I'he liquid situated' beneath the piston of. d can then now away through Di and through the controlling slide to f. The pressure liquid still remains on the valve spindle side of the controlling. cylinder c, the return ow pipe i1 of which is, however, closed by the stop valve V2 until the pressure in the pump chamber of the cylinder Zahas become so low that the stop actionof the piston oi V2 has been removed, 'I'he controlling liquid can then iiow away through Dr.

- In the position of 4 the auxiliary controlling slide vS shown, thefollowing valve movements are accordinglyeffected positively: y After filling the cylinder Z up to a predetermined level with -initial lproduct the 'inlet valve A -ls closed, thereupon the controllable ch'eck valve C is opened, whereby the product is reduced from pressure down to the low counterpressure of the lling pipe n.' Only after complete reduction of pressure of the product to the low iilling pressure of the pipe n can the outlet valve B open, whereby the pressure-reduced product is then forced out from the cylinder Z by the pressing down of the lpiston K by the low lling pressure from the pipe n.

.Shortly before reachin of the piston K, the a g 'the end of the stroker uxiliary controlling slide manner by the piston rod. After this reversing, the pressure liquid'ilowlng r'stly enter through the check valveRz into on the valve spindle side of the piston and secondly through the check valve R4 into the con- The liquid situated on the valve spindle side of the controlling cylinder c ttle valve Ds, through g2, controlling slide S and through f. 'I'he dam pressure set up in front of D: during the piston movement of the controlpiston c is conveyed vto the stop valve V3 and keeps it closed until the stress of the piston in the controlling cylinder c is completed.v Only then'can the piston of the controlling cylinder e be set in'motion. The dam pressure'produced e of the controlling cyler e is conveyed to the stop valve V4 and which, by its construction, only sets freethe turn pipe g1 between the controlling cylinderfb andv the stop valve V4 and consequently' fellows the movement of the piston of thecontr'olling cyl sure is present in the der. I,

Then the controlling pistons of the controlling slide S areg-reversed and are situated at the righthand sidei the following valve movements are thus effected:

After eJecting' the pressure the outlet valve B is close check valve E is' opened so tion of the cylinder Z is pla surejand after reachin ter-pressure above the A' is'opened and the initial product sluiced into the cylinder Z. 'I'he sluiced-in product then moves the piston K until the piston rod again reverses the auxiliary controlling slide S in known manner, .whereupon the operations already described are repeated. y

The improvements'and -apparatus herein depump portion of the ,cylin- -reduced product,

g the desired high coun- 25 scribed and claimed are of particular advantagev for the reduction of pressure onthe products of hydrogenation or destructive hydrogenation under high pressure, of distillable carbonac'eous materials, such as coals of various sorts, tars, mineral oils or products of distillation, conversion or extraction of any of them. 'Ihe process is in particular beneficial, forvthe reduction of lpressure-on the residues containing solid matter withdrawn from the reaction vessel orhot catchpot .in the -destructive hydrogenation of coal. The products .thus reduced in' pressure can be more readily filtered orcentrlfugedathan the products from whichpressurehas beenr reduced according to the methodzhritherto Pressure reduction of anypracticahdegree may 'I be effected, for example, .fromglOOO .atmospheres or more, 700 atmospheres,v 300 atmospheres down to about atmosphericpressure. i l

What we claim is:

.1. An apparatus for 'reducing the pressure of cylinder,

the controlling cylinder b GG/pelling said keeps it closed untilv the piston of the' control- 1 ling cylinder e has completed its stroke. Only then is the return 'pipe from the side of the larger piston surface of the controlling cylinder b set free through'Vi to Ds. Between V4 and the out- -let of the controlling cylinder b is situated in the pipe g1 afurther. stop valve Vs thespring-loaded quantitylof the mixt working fluids which comprises a cylinder having a oating member therein, means for forcing said floating member toward one end of the means for conducting the working uid into the cylinder without substantial loss in pressureagainst the forceexerted by the rstnamed means this force being slightly less than that of the working fluid acting on the oating member, means -for cutting ol'the supply of said working uid, means for reducing the force applied to the oating member by said first named means while confining the working iiuid within the cylinder thereby reducing the press'ure on said confined working fluid, and me'ans forexworking uid at the-reduced pressure.

mixtures of liquids and gases which comprises in combination a cylinder having a' movable piston therein and valves at each end of said cylinder, means for conducting a high pressure auxiliary liquid having a pressure approximatelyequal to that of said vmixture but only so high that the force `acting o the floatingy member is slightly less than that o? the working fluid acting on theother side of the iioating member into one end of the cylinder, means for conducting a into the other end of the cylinder without subs antial loss in pressure 5 against the pressure set up 'by the auxiliary liqinder b when a correspondingly .higher preisd, the `controllable that the pump por-A ced under high prespiston K the inlet valve 2. An apparatus for reducing the pressure of uid whereby an equal quantity of high pressure auxiliary liquid is forced out of the cylinder, meansfor cutting oi the supply of said mixture and said high pressure auxiliary liquid, means for reducing the pressure, after the operation of said cutting-off means, of the auxiliary liquid and the mixture while the latter is conned within the cylinder and means for expelling the mixture from the cylinder at the reduced pressure.

3. The apparatus as claimed in claim 2 wherein the movable piston within the cylinder is guided by a piston rod extending through the end oi' the cylinder into which the auxiliary liquids are introduced.

4. The apparatus as claimed in claim 2 wherein the pressure reducing cylinder is in an upright position.

5. The apparatus as claimed in claim 2 in which the means for controlling the valves of the pressure reduction machine are dependent on the pressure within the cylinder.

'6. The apparatus as claimed in claim 2 wherein the pressure reduction machine has an upright cylinder, a piston the rod of which extends through the top of the cylinder and is so dimensioned that the unit pressure of the said high pressure auxiliary liquid introduced above the piston can be higher than the original unit pressure of the mixture While the total pressure of the auxiliary liquid on the piston' is less than that of the mixture and the means for controlling the valves of the pressure reduction machine are dependent on the pressure within the cylinder.

'7. The apparatus as claimed in claim 2 wherein the valves of the pressure reduction machine are controlled by means of an auxiliary controlling slide.

8. The apparatus as claimed in claim 2 wherein the valves of the pressure reduction machine are controlled by means of an auxiliary controlling slide for which the said high pressure auxiliary liquid is used as pressure liquid.'

9. The apparatus as claimed in claim 2 wherein the proper sequence of valve controls necessary for the pressure reduction is effected by the dam pressure of a controlling liquid issuing from hy` draulically controlled valves and by the internal pressure in the pressure reduction cylinder in cooperation with check valves. l

10. The apparatus as claimed in claim 2 wherein the valves of the pressure reduction machine are controlled by means of an auxiliary controlling slide, for which thesaid high pressure auxiliary liquid is used as pressure liquid, the proper sequence of valve controls necessary for the pressure reduction is eected by the dam pressure of a controlling liquid issuing from hydraulically controlled valves and by the internal pressure in the pressure release cylinder in cooperation with check valves.

FRANZ KOEHLER. MAX JOSENHANS. 

